Lye-Ability: Making Castile Soap

I always thought soap making would take a lot of specialist equipment and expensive ingredients. But like so many things when you dig deeper, soap making can be done on the cheap. I chose Castile soap for my inaugural soap making experience. Why? Castile soap is expensive to buy; it has been known for hundreds, possibly thousands of years for its gentleness to skin AND I could get all the ingredients I needed at the grocery and hardware store.

If you want some economical but super swanky Christmas gifts, this soap fits the bill. As one recipe will give you nearly 2kg (4.4 lbs) of soap, you can gift half your list for less than NZ$15. In fact, if you add some tissue paper and print up some jazzy “hand made” labels for your bars, you’ll probably spend as much on the packaging as you do on the soap. Plus you’ll get to wear the “I-give-the-most-fabulous-gifts” crown. They will be impressed. Just note that your soap will need to cure for 3-4 weeks minimum before you give it away. So start now.
Time to gather your ingredients and equipment. You’ll need 1.4 l (48 oz) of olive oil. Go cheap, no need for Extra Virgin Olive Oil here. If you can get B Grade Olive Oil (non-food grade) even better. Otherwise just buy the cheapest stuff you can find at the grocery store. I got mine at Pak ‘N’ Save for $9.99/litre.

Castile soap is known for its gentleness, but not its lather, so don’t expect any big suds out of these bars. In fact, if it doesn’t lather up when it is cured, you’ve done it right! If you want a more sudsy experience, substitute a few hundred ml of coconut oil for some of the olive oil. You won’t have a pure Castile any more, but you’ll get more bubbles.

You’ll also need 170g (6 oz) of lye aka caustic soda aka sodium hydroxide. The hardware store is the place to go for this ingredient. Look in the drain cleaner aisle. That is what it is used for, so treat it with respect. Also make sure you purchase PURE sodium hydroxide, some preparations, like Draino, are only part sodium hydroxide. You need the full strength stuff. I found mine at the Mitre 10 Mega in Albany at NZ$10 for 500g. Also check out these 5 Important Steps for Safely Working with Lye and keep some vinegar close to you when working with lye in case of spills.

Next you’ll need protective gear. Rubber gloves, safety goggles and an apron to protect your clothes are all good ideas. You’ll be wanting to do this project in long sleeves, long pants and wearing shoes. I don’t have safety goggles lying around, so I used my snorkel mask. STOP LAUGHING! It worked and didn’t cost me anything extra.

Because you are working with lye, this is absolutely, positively NOT a young kid-friendly activity. You saw Fight Club, right? You won’t want the nippers anywhere around when you are doing this. A lot of home soapmakers work at night for this very reason. However, if your offspring are old enough to go to take Chemistry, they might get a kick out of some practical application.

You’ll also need to own or borrow at least one thermometer (two is better, but I managed with one), a scale, a large stainless steel sauce pan and a stick blender. You can get away without the stick blender, but it will turn minutes of stick blending into HOURS of blending by hand. I kid you not. Sure, your great-great-grandmother managed with less when SHE was making soap, but we are going for modern gift quality bath products here.

Finally you’ll need mould for you soap. You can get cute fancy-schmancy ones or go cheap. No prizes for guessing how I came down on this one. I used half a wine box, an old cat food container, two yoghurt pottles and a small round container from the last time we got gravy on the side with our takeaway roast dinner. Shoe boxes are also an excellent choice. You’ll want to line any larger moulds with baking, wax or butcher’s paper all shiny side down.

If you want pictures of the process have a look at SoapChix’s 13 Steps to Cold-Processed Castile Soap. They use a slightly different recipe that makes a bit less soap at a go but step No. 2 in their tutorial is “get dark chocolate and peanut butter.” I like their style!

Cold-Processed Castile Soap

Wearing your HazMat gear and working in a well ventilated area, measure out the amount of lye you need. Pour CAREFULLY into the pre-measured water and stir. Always pour lye INTO water, not the other way around or you’ll end up with a lye volcano. Not good. Don’t inhale the fumes. I did this bit outside to prevent fumes from lingering in my kitchen.

Lye when mixed with water is massively exothermic. That means it is going to get hot. Very hot. About 100C (212F). You’ll need to keep an eye on temperature of the lye and add it to pre-warmed oil when it hits around 38C (100F). I got tired of waiting after 30 minutes and transferred the container filled with lye solution into my kitchen sink filled with cold water. That sped the cooling considerably.

As the lye approaches 38C (100F) you’ll need to warm your oil to the same temperature. When they are both about 38C, carefully add the lye to the warmed oil. Blend, moving the blender in a figure eight pattern and keeping the blender fully immersed. Follow the instructions for your blender on how long you can blend at one time. Mine can go for 30 seconds then requires a 1 minute rest.

Blend until you reach the thin trace state. This is when the mixture just starts to thicken. At this point you can add any extras you want in your soap, Essential Oils (you’d need about 30ml (1 oz) to scent a batch this size), oatmeal, flowers or leave it a Pure Castile by adding no extra ingredients. Once you’ve added any extras continue to blend until you reach medium trace when the mixture looks like thin pudding.

Pour soap mixture into the moulds you prepared earlier. Wrap with a blanket or towel and place in a safe place that won’t be disturbed for the next 18-24 hours.

After 18-24 hours, your soap should have set. Press on it gently and you should leave a small indentation. If it isn’t set, leave it until it does. If it has, remove soap from moulds and pull off any lining paper that may have stuck. If you lined your moulds smoothly, you should have smooth sides on your soap, if you were less picky about it, you’ll get something similar to my picture below.

Next you’ll want to carve off any messy bits and cut the bars into their final shapes. Your soap will become harder and harder to cut as time goes on, so you’ll want to cut now when it is easiest.

Save the off-cuts, it is still soap! I’ll be using my off-cuts for home made laundry detergent, liquid dish detergent and some hand-milled soap later on.

Now for the hard part. Waiting for 3-6 weeks as your soap cures. Place your soap on a cookie cooling wire rack, plastic “in-box” or stand on the thin edges and store in a warm, dry place like the hot water cupboard. Turn once a day for a week, then once a week for the remaining cure time. When cured, store in an air-tight container.

You CAN use your soap earlier. It won’t be as mild, durable or as hard as it will be later, but you won’t kill yourself if you use it sooner and the pH is reasoanble. You’ll just use it up quickly and it will be harsher on your skin until the pH drops as part of the curing process.

Kiwis, want to get all your soap making supplies including oils, essential oils, dyes and moulds in one place at competitive prices? The Frugal Kiwi recommends the excellent online shop Soapcraft Aromatics and More.

Ready to go über frugal? Learn how to make Kitchen Grease Soap over at Little House in the Suburbs. Mmm, bacon grease soap!

***Important Safety Note from Professional Soap Maker and my personal Soap Guru Leanne of Feel at Home. Have a look at her site and try not to drool too much over the beautiful 3D felted soaps. And her Cinnamon Mandarin soap is to die for.

Wonderful Tutorial – well done. Soap looks good! Just one point I feel I just MUST say – PLEASE test the soap for proper pH – sometimes soap can take 6 weeks, and if proper measuring was not done, no amount of curing will give the proper ph, and one christmas present your friends will never forget, is an alkali burn! ph testing kits can be bought at a hydroponics store. PH test strips work well and is a small price to pay for a good experience with homemade soap.

Soap should always be about 9.5 – never more than 10. skin itself is about 7.5 and that is only achievable with the addition of an acid to the soap (dove beauty bar etc..) Soap by definition is an alkali agent that cuts through grease and dirt. Natural soap, which has not commercially had the glycerine content removed, allows skin to recover its natural balance more quickly with less damage than soaps that do not have natural glycerin… so shoot for a pH of approx 9.

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Brittany
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November 30, 2014

Not sure if that was in reply to me but if so… there are 148 comments and I did read some but not all and all I was asking for was if you had a link to a similar recipe or if you could just say “it’s the same process but with less ___ / more ___ / etc” but okay that was an unhelpful reply. See ya.

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I had to laugh at the snorkel goggles! Lol. Only because I do the same. Whilst I’ve never made soap before and am now looking how to do it to give away as presents, I actually just used my snorkel goggles to chop some wood up, but….. the actual snorkel is wedged on pretty tight into the mask. So yeah, you guessed it I chop wood with full snorkel head gear! Lol.

Anyway, thanks for writing this, it’s very helpful. I think I will add some coconut oil into the mix as I like a good lather. Does it matter what kind of coconut oil? I ask because I buy virgin coconut oil as I am on a weight loss diet (it’s digested directly to energy, as opposed to being stored as fat like other oils). But that stuff is pretty expensive. I can get a cheap hydrogenated kind of coconut oil, would that work?

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Hi, I made the Castile soap following your recipe. I used sandalwood essence to give it a male perfume. Now that my soap is cured and ready to use (ph 8) it still smells very chemical. Is that normal or did I use the wrong equipment? How do I get rid of that chemical smell or do I trow everything out? Please advise.
Martine

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I’ve never had soap come out smelling chemically. My first guess is that you over did it with the sandalwood, which can be pretty darn strong. For advice from soaping pros on this, post your question to the Soap Making Forum.

[…] Traveller, brief explanations of soap making don't seem to exist. Here's the method I followed: Lye-Ability: Making Castile Soap First batch was successful, I am still reserving judgment on the second. Annie's Primal […]

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Kelly
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April 25, 2013

Hi, I’m planning on substituting a ‘few hundred ml’ of olive oil for coconut oil simply because I have some in the cupboard. Olive oil will obviously be easier to buy in a 1L bottle so would substituting 400ml be ok? (Considering the 1.4L in the recipe). I assume that it will just create more suds, is this correct or will I have a disaster on my hands? Thanks.

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It would probably be fine, but to be on the safe side, you can run your new recipe through the calculator at SoapCalc to make sure the change won’t change the amount of water and/or lye you need. Adding coconut oil in will give it more suds and make it a harder bar, which isn’t a bad thing, given how soft olive oil only soap is. More information on using SoapCalc and designing a soap recipe at How to Design a Soap Recipe.

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Alice
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March 16, 2013

Hi
Thank you for your informative and helpful tutorial on soap making! I must say it’s the best one that I can find online! 🙂
I have a question: Can I use this simple castile soap as shampoo soap and use it on my hair? 🙂

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Miss Gizzy
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March 11, 2013

Hi,
Doh. I realised after I mixed the lye and olive oil together and pored it into my mold that I had used waaaaay to much lye. Way, way, way too much. Several times the right amount too much. I had followed all the other instructions. When I took the soap out 24 hours later and tried to cut it it was hard and split/shaved when I went to cut it. There were no lye pools in it, but there were teeny, tiny bubbles.

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Mrs G
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March 5, 2013

Hi, I would like to make this soap as my first attempt in soap making. I’m a bit scared in handling caustic soda, though.
I have a question: do you use a pan you normally use for cooking or you use one just for soap making? And what about the mixer? After a good wash, would it be ok to mix my soup with it or better have a different one? What about spoons, measuring cups, etc?
Thank you!

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It is up to you, really. Some people have completely separate kit for soapmaking. I don’t. In fact, whenever I make soap, I take some of the uncured soap goo and pour it on the bottom of any pot in the house that is a bit stained. I leave it overnight, then cleaning it up in the morning. Quick and easy stain removal!

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Hi was jut wondering could I make a batch of this wait for it to cure then use as a melt and pour base? Wanting to try make a soap for my son who has eczema and very sensitive skin also a soap for my mum who has burns.

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No, you can’t use it as melt and pour as “glycerin soap” used for that craft is quite different. You can however, use this recipe for rebatching/handmilling. There are recipes out there for making your own M&P, but this isn’t one of them.

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Diana
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February 3, 2013

So glad you are here!!
I want to make my own natural laundry liquid – totally using your recipe. I also bought some cloth nappies for my third baby due in a few months from trade me. I read from a nappy “expert” not to launder cloth nappies in any kind of oily ingredient. BUT I really wanted to use your castile soap. I’m lost as to what other kind of soap to use from the supermarket as the whole point for me to change from chemical laundry powders to this is not only to be frugal but natural and healthy.
Also, if you have been in Binn inn orewa recently they have new owners and they are selling lidded buckets of coconut oil for approx $4o . (Baby brain!)
Please can you tell me what soap I should use for the laundry and if so can I use this castile soap – bearing in mind the nappies? Thanks 🙂

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I’ve used my castile with good effect, but not washing nappies. The thing with this recipe is that it is so inexpensive, that you don’t lose much when you experiment. If you find you want different soap, gift your old recipe to a friend. You can always make a half, quarter or eighth recipe to try.

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KellyAnn
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November 29, 2012

I have gotten into making homemade cleaners and detergents.. Well most of my recipes call for castile soap.. which I couldnt find any where!! went to 3 different stores and no one knew wat i was talking about and since i got all my recipes from pintrest I look this one up!!! So just wanted to say thank you so much!! I am deffently going to try this!!

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Either your measurements were off on the lye or the lye water and oils were mixed together when the lye had cooled off too much. You can rebatch if there are no lye pockets in the soap. Try over at The Soap Forum for more info, if you want it.

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Its also possible that your batch overheated. Mixing the lye with melted oils at room temperature is perfectly OK, as long as you get your oils to at least 130 degrees F first. The hotter the lye water and/or oils is only speeds up the rate of saponification – it makes “trace happen quickly”. Test your soap for zap – wet your finger, run your wet finger over the surface of the soap then touch your finger to your tongue. If it feels like a 9-volt batter shocked you, that is zap. If your soap is zappy after 3 days after you unmold you can consider it lye heavy. Then you can rebatch it. You can gel your soap – that is when the soap heats up under the chemical reaction its going through and goes through a gel phase. The colors tend to be darker if you used any colorants, but some recipes are more prone to overheating than others (like if you use milk or sugar in your recipe, some essential oils and fragrance oils can also cause overheating.) You can force gel by insulating your mold, or reversibly, you can inhibit gel by putting your mold in the freezer. It will take longer for the soap to be hard enough to cut, but either way should work fine – its a matter of preference. Keep trying in small batches, you will get it eventually and then you will be hooked!

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Thanks for the input. I have absolutely had a batch fail due to mixing the lye in too cool though. A used recipe, same as always, but I got pulled away and the lye solution was cooler than usual when I mixed. The results were not good.

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@FrugalKiwi Thanks for the encouragement & the tutorial. I’ve been wanting to make my own high quality & skin friendly soap for AGES. I’ve been using a preparation from soapnuts in my hair, but soapnuts smell like wet dog so that’s going to get relegated to hand soap use only….

Quick question… what kind of pot do you make the soap in, and is there a chance that lye will react badly with some metals?
I’m eyeing up my mother’s old preserving pot, I’m not sure what it’s made from exactly, but she won’t use it for jam making anymore on the off chance that she poisons us all (it’s a light hazy silver in colour – maybe looks like aluminium?).

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Excellent question. Use stainless steel pots ONLY-never aluminium. Plus there is one resource that every new soaper should know about, the Soap Making Forum at http://www.soapmakingforum.com/ Recipes, tips, moral support and super friendly people. Don’t miss it!

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chocolatemama
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March 4, 2012

Hi just want to know how long this process will take? Other recipes say you mix it for an hour or two! I don’t have that kind of time with littlies! Also a crazy question but I want to make breastmilk soap, could I add this when you suggest adding the essential oils etc? And what amount would you recommend? Thank you!

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@chocolatemama How long the whole process takes depends on if you cool the lye down in a water bath or not. I usually do. As for mixing, we are talking 5-10 minutes with a stick blender, not hours. But I would always suggest you do any soap making as a post-bedtime for littlies activity. They need to be fully out of your hair.

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You CAN make breast milk soap, use it in place of, or as part of your water from your recipe and freeze it into ice cube trays first. Then place your lye directly on the frozen milk/water to dissolve. Freezing can help with the problem of overheating. Milk soaps tend to overheat, so after mixing it to trace, you should place it in the freezer for a day or two to finish “cooking”, then remove it from your mold and cut it when its hard enough to cut, but not so hard that you cant cut it.
Remember to always run your recipe through a lye calculator, food grade olive oil, pomace olive oil and extra virgin all have different saponification values and will require different amounts of lye to make soap safely. One should not simply substitute equal portions of any oil in a recipe – you could end up with lye heavy soap or a gloppy mess that no cure time could fix. http://www.soapcalc.net has a good one, and they have recipes too!

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meremaiden
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January 29, 2012

Hi– just in reference to your comment about making liquid castile soap as a very time-consuming process– wouldn’t it just be as simple as this?:

Liquid Castile Soap Recipe

1 cup firmly packed grated Castile soap (about two 4 oz. bars) 4 cups water 2 tablespoons vegetable glycerin Before you begin, grate the castile soap with a cheese grater. Try to shred it as fine as possible since it will take less time to melt the soap down if the pieces are small. Mix the grated castile soap with the water in a large pot. Set over low heat, stirring occasionally until the castile soap has dissolved. Add glycerin. Keep your eye on it! Once dissolved, transfer to a jar and cover tightly. This makes a thick liquid soap. For a thinner liquid soap, add more water until desired consistency is reached.

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This will make a gel sort of soap, similar to what I mentioned to barneyhairball below, not a true liquid soap, which is what she is looking to have. I’m all for what you are talking about and it would suit me just fine-in fact it is fancier than what I do for myself- but it probably isn’t what she is after. Of course, she can decide for herself!

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KissandraArcher
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January 27, 2012

Hi We have made this batch of soap before and havent had a problem! 🙂 But we just did our first batch adding oil.. When the oil was mixed the soap became a soild mass with in seconds? Help!! Feeling a little frustrated!

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@barneyhairball Making liquid soap is a VERY complex process. If you want something simple take your solid castile, grate it up, mix it with hot water and you can make a gel sort of castile with little fuss. If you want to make true liquid soap, get book and plan to spend quite a lot of time perfecting the process and it WON’T be just those three ingredients.

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barneyhairball
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January 27, 2012

@FrugalKiwi@barneyhairball Hi there, why do other ingredients need to be added? Is the answer, buy a book!? i’ve already melted down castile soap, so now want to make the real thing. There is a site from Canada that makes liquid castile and the ingredients are just water, olive oil and lye – are they telling fibs?

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@barneyhairball For a nice clear tutorial of liquid soap making (without buying the book) check out this great site http://www.islandartisansupply.ca/liquid/ PS-They aren’t telling fibs, depending on how clear you want your liquid soap, but truly, it isn’t a simple process and don’t do it until you’ve mastered solid soap making.

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barneyhairball
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January 29, 2012

@FrugalKiwi @barneyhairball Hi again. Bought the book! Failor gives a recipe for Castile shampoo only, but then states it is the same recipe as for soap. In said recipe she uses alcohol (but doesn’t state empahtically that it is needed; IS IT NEEDED?); she also neutralises it with borox or boric acid; WHY DOESN’T THAT WEBSITE FROM CANADA USE THIS? If not using it, does this website not neutralise? Getting even more confused! Any advice?

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@barneyhairball I’d say, ask the Canadians. I haven’t actually gotten around to making liquid soap yet since gelled soap meets my needs and takes seconds to sort out. I’ll do it one day, but that day hasn’t come yet. I’ve read Failor’s book, but obviously not put it into practice.

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Bcanadian
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March 8, 2013

My first attempt at any cold process soap was liquid 100% pure olive oil Castile soap: olive oil, potassium hydroxide and distilled water. Did it all in a slow cooker / crock pot and it came out like honey and perfect, not difficult at all, just very long ( lots of stirring and several hours are required). There is a lovely tutorial by silverfirsfarm on you tube. Good luck!

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you can try to search for recipes with potatssium hydroxide, instead of sodium hydroxide- that is the main difference between solid soap and liquid soap. of course there are other additives that are needed too, as preservatives, etc.

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@Mere You can do it with a spoon if you want, but it will take you several hours instead of a few minutes. Until you know what trace looks like, I’d suggest you buy or borrow a stick blender. You probably have a friend or relative with one and they might want to get in on the action or at least be willing to get some soap out of it for the loan of their stick blender. Good luck!

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@Mere Yes, I know you did. The answer is still the same. You could do it by hand and it will take several hours. You could do it with an electric hand mixer and it might take an hour and a half instead of several hours or it might take 45 minutes. You might burn out the motor of your hand mixer. A stick blender will take a few minutes tops. If you don’t know what you are looking for, you should use the option that will take the least time, so you don’t ruin your equipment and make yourself nuts wondering if you’ve seen trace yet! Good luck.

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YvonneSymons
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January 3, 2012

For those looking for a cheap mold The Warehouse has a lovely flower one for about $5.00. I used it for my first batch and they have worked well. Have since made another batch with coconut oil. I think we need a NZ soap forum. Any thoughts?

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JessicaCopplestone
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December 27, 2011

Hi,

Thanks for the soap recipe, it was so easy to follow. I made my first batch with coconut oil and orange essential oil and gave it as christmas presents. You were right, I totally got to wear the “I-give-the-most-fabulous-gifts” crown, lol

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Mary, I provide volume and weight for the liquids. Oz is a unit of weight (fluid oz is a unit of volume) but mls and litres are units of volume. Different people like to work in different ways. I always prefer weight, as I feel it is more precise for me to measure.

As for the color, did you by any chance use a wooden spoon? I suspect you might have and the alkali of the solution has eaten into your spoon and coloured your soap with the wood. If you have, next time use a stainless steel or silicone stirring implement.

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AndreaMarie
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December 22, 2011

Hello, I made this, but I wanted to really bling up my soap. I did one batch, and poured it into a shallow sided cookie sheet. After it set, I cut out hear shapes with a cookie cutter, and have those. I then did another batch of soap, and added beet juice and poured this pink color into the empty heart spots. Once that set, I cut it all into bars. So, now I have rectangle bars with a pink heart inside and one pink side. I hope these work and the beet juice doesn’t do anything funny to it!

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YvonneSymons
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December 11, 2011

Great thank you for that. was at Mitre10 yesterday and got passed onto 4 different people. no body knew anything and couldn’t say if any of the products was 100% caustic soda. A job for after Christmas now.